Lubricant composition



Patented Nov. 5, i946 HUBBKCANT CQEIPGSEEIKQN No Drawing Application March 39, 194d, :derial No. 528,783

- 9 Claims. (oi. ass-sac) ihis application is a continuation-in-part of copending application Serial No. 390,586, filed April 26, 194i, and relates to hydrocarbon ollsof the type employed as lubricants, dielectrics, and the like. Primarily, the present invention is concerned with improving certain characteristics of such oils, particularly pour point and viscosity index, and stabilizing the oils against the detericrating influences encountered under operating conditions.

as is well known to those skilled in the art,

petroleum oils of the viscous type refined for use as lubricants or the like are generally subject to deterioration in service with the iormation of acidic materials, sludge, and other oxidation products which reduce their usefulness. li/l'otor oils, for example, and particularly those used in the lubrication of Diesel engines, are subjected to 'relatively severe conditions which accelerate the development of acid and sludge in the crank case and the accumulation of lacquer and carbonaceous material about the piston rings, which cause the rings to stick and which obstruct the oil slots therein. The acidic materials developed tend to corrode certain hard alloy bearing metals such as those having the corrosion-susceptibility of cadmium-silver alloys and the like.

This invention is based upon the discovery of a novel class of addition agents which when blended in minor proportions with hydrocarbon oils of the type above-referred to will effectively retard the deterioration imposed-by either mild or severe conditions of use and will therefore miscibility or oil-solubility to the compound or reaction product.

The present invention contemplates compounds of the class described wherein the oil-solubilizing action is obtained from an alkylated aryl nucleus which, in addition to oil-solubility impartspourdepressant properties to the compound or reaction product. The pour-depressant property is obtained by employing an aryl nucleus which .is

substituted with relatively long-chain alkyl groups, such as those characterizing parafin wax (predominantly alkyl groups or" at least twenty carbon atoms). A compound or reaction product of the type contemplated herein may be broadly described as an oil-miscible metal salt of a thio acid of phosphorus or, more specifically, as a metal salt of a partial ester of a chic acid of phosphorus, ob- .tained by reacting Pass with a compound having the general formula ROH wherein R represents an alkaryl oil soluhilizing hydrocarbon group of the type described above and then reacting the product thus obtained with a reactive metal compound. Although, as aforesaid, we do not wish to be bound by any theory of reaction or formula of the product, it does appear that under certain conditions of reaction and reactants the ultimate products obtained are the metal salts of waxsubstitut'ed diaryl dithiophosphcric acid, the general structural formula of which may be expressed as follows:

wherein Rn represents at least one alkyl group having at least twenty carbon atoms or an alkyl group corresponding to the aliphatic hydrocarbons characterizing paraifin wax, and M is as defined above. As aforesaid, howeventhe formulae and nomenclature 'used herein are based upon our theory of the reaction and are intended to represent the reaction product obtained rather than a specific chemical compound in each instance.

It is to be understood that the aryl nucleus in compounds of the type represented by the foregoing general formulae (I and 11) may be monoor poly-cyclic and, as aforesaid, the alkyl substituent thereon should correspond to an alkyl group of sufiiciently high molecular weight to impart to the compound pour point-depressing and viscosity index-improving action in addition to oil miscibility. For alkyl substituents that will impart these properties, particular preference is given to alkyl groups of at least twenty carbon atoms.

As to the metallic constituent M, it appears that any metal may be used. The alkaline earth metals are preferred, with particular preference given to barium. Other representative metals which may be used are zinc, tin, aluminum, cobalt, nickel, chromium, the alkali metals, etc.

As aforesaid, the reaction products contemplated herein as typified by the metal salts of the partial esters of dithiophosphoric acid may be prepared by first forming the corresponding partial ester of dithiophosphoric acid by any known method, such as that described by P. S. Peshchimuka (J. Russ. Phys. Chem. Soc. 56, 11 (1925) (Chem. Ab. 19, 2808) wherein phosphorus pentasulfide is reacted with an alcohol, and then reacting the partially esterified acid thus formed with a metallic hydroxide to form the metal salt of the partial ester of dithiophosphoric acid. The reactions involved can probably be expressed by the following equations, although, as aforesaid. we do not wish to be bound :by any theory of.

reaction.

(A) 4ROH+P2S5+2 (R) zPSSH-I-HaS (B) (R0) aPSSH-i-MOH. (R0) zPSSM-I-HaO As a modification of the foregoing procedure reaction (B) may be carried out with sodium or potassium hydroxide (M'OH) to form the corresponding salt (R0): PSSM', which can then be reacted with a water-soluble salt of another metal, such; as zinc chloride or stannous chloride, to yield by metathesis the substituted dithiophosphoric acid saltj'of the second metal.

Further detailsf fthe procedure which may be followed in synthesizing the compounds contemplated herein, may be obtained from the following illustrative examples.

EXAMPLE 1 Min-AL SALTS or Dn'mornosrnoarc -Acm Wax-substituted was first prepared by the Friedel-Crafts condensation of chlorinated paraflin wax (16 per cent chlorine content) with phenol in the ratio of 1 molecular part phenol to 3 atomic parts chlorine in the chlorwax. The

wax-substituted diphenyl dlthiophosphoric acid was obtained by making a reaction mixture of 100 grams of the wax-phenol, 8.1 grams of Past, and 300 grams of mineral oil of Saybolt viscosity of 6'? seconds at 210 F. This mixture was heated at 100 C. until the evolution of H28 had substantially stopped (about or hours). The clear solution was then blown with a stream of phenyl dithiophosphoric acid (3-16) in approximately 25 per cent mineral oilblend.

The stannous salt of "Wax-substituted diphenyi dithiophosphoric acid'was obtained by dissolving 100 grams of the acid product obtained by the procedure last described above (dissolved in 300 grams of mineral oil) in 100 cc. of butyl alcohoLadding 1.5 grams of metallic sodium, and

' heating the mixture at the reflux temperature of the alcohol until the sodium was all reacted. A

butyl alcohol solution of stannous chloride (6.2

grams of SnClz) was then added and the mixture slowly heated to 150 C. while the alcohol was distilled oil. The mixture was then cooled,

diluted with benzol, and filtered through a filtera filter-aid clay to remove unreacted Ba (OH) 28H2O,

and the solvent was distilled oi! to obtain the finished product. a

Typical metal salts of partial esters of dithiophosphoric acid which have been synthesized and demonstrated to be effective addition agents for hydrocarbon oils of the type used in lubricants and the like are the following:

Stannous di(wax-phenyl) dithiophosphate Barium di(wax-phenyl) dithiophosphate The following examples will illustrate the effectiveness of the compounds contemplated herein to stabilize and improve the various properties of various viscous hydrocarbon oils.

EXAMPLE 2 CORROSION Tssr v The corrosion-inhibiting action of these compounds was demonstrated in the so-called catalyzed Underwood oxidation test, which is described in a pamphlet, dated August 1, 1938, of the Research Laboratories Division of the General Motors Corporation, entitled fUnderwood oxnitrogen to remove entrained H118, to obtain the product which, for purposes of identification herein we may refer to as wax-substituted diidation testing apparatus. The following results were obtained by using a motor oil of 210 seconds Saybolt viscosityat F. with the addition of sufiicient iron naphthenate to be equivalent to 0.01 per cent iron oxide to act as a catalyst. Bearings containing a cadmium-nickel surface were used and the Mg loss in bearing weight and the acidity bf the oil (N. N. value) were determined after five hours of test.

Compound added gg; N. N.

None 789 13.4 Ba salt of wax-substituted diphenyl dithiophosphoric acid (3-16) 1 40 2. l

EXAMPLE 3 Form Dnrxsssam AND V. I. IMPROVEMENT As aforesaid, the so-called wax-substituted compounds have the properties of acting as pour point-depressants and viscosity index-improvers.

These properties are demonstrated by the results set forth in Tables 11 and m below showing pour point-depressing and V.. I. results, I respectively. on typical motor oils with and without the addition agent.

Table II g A. S. 'I. M. pour .Compound blended with motor oil of 67 sec. points on on Hands Baybolt viscosity at 210 F.

F. F. F. None +20 Barium salt of waxsubstituted *diphenyl dithiophosphoric acid (3-16) 10 -20 Table III Kinematic viscosity Compound blended with C v lubricating oil Per can't None o 29. 56 4. 72 76. 7 Waxeuhstituted diphenyl dithiophosphoric acid (3-1 1 32. 28 5. 04 86. Barium salt of wax-substt tuted diphenyl dithio- I phosphoric acid (3-16)... 1 33.06 I5. 15 89.6

Tables I, II and III and in Example 1 above indicates the number of atomic proportions (3) of I chlorine in the chlorwax reacted with 1 molecular part of phenol and the percentage (16) of chlorine in the chlorwax used in this reaction from which the wax phenol was obtained. This wax'phenol (3-16) provides the wax-substituted phenyl substituents in the salts disclosed herein, as described in Example 1.

The compounds or reaction products contemplated herein may be used in various amounts depending upon the character of the oil and the severity of the conditions under which it is to be used. In general it appears that satisfactory improvement may be obtained with amounts ranging from about 0.01 per cent to about 5.0 per cent.

It is to be understood that while I have herein described certain specific compounds and procedures to illustrate the invention, such specific examples are illustrative only and the invention embraces within its scope such changes and modifications as fairly com within-the spirit of the appended claims. I I

I claim:

1. A lubricant composition comprising a major proportion of a. viscous hydrocarbon oil and an oilmiscible metal salt of a substitutedthio acid of phosphorus having the general formula PSM in amounts sumcient to exert detergent and anticorrosive properties in the oil under heavy duty service, wherein Rn represents at least one oilsolubilizing alkyl group containing at least twenty carbon atoms and M represents the hydrogen equivalent of a metal.

to exert detergent and anti-corrosive properties in the oil under heavy duty service, said wax group containing atleast twenty carbon atoms.

4. A lubricant composition comprising a major proportion of a viscous hydrocarbon oil and an oil-miscible metal salt of a wax-substituted diphenyl dithiophosphoric acid in an amount sufflcient to exert detergent and anti -corrosive properties in the oil under heavy duty service, said wax group containing at least twenty carbon atoms.

5. A lubricant composition comprising a major proportion of a viscous hydrocarbon oil and an oil-miscible alkaline earth metal salt of a waxsubstituted diphenyl dithiophosphoric acid in an amount 'suflicient to exert detergent and anti= corrosive properties in the oil under heavy duty service, said wax group containing at least twenty carbon atoms.

6. A lubricant composition comprising a major proportion of a viscous hydrocarbon oil and an oil-miscible barium salt of a wax-substituted diphenyl dithiophosphoric acid in an amount suflicient to exert detergent and anti-corrosive roperties in the oil under heavy duty service. said wax group containing at least twenty carbon atoms.

7. A lubricant composition comprising a majo proportion of a viscous hydrocarbon oil and an oil-miscible zinc salt 01 an acidic reaction product obtained ,by reacting PzSs with a compound having the formula:

in an amount sumcient to exert detergent and anti-corrosive properties in the oil under heavy duty service, wherein Rn represents at least one oil-solubilizing alkyl group containing at least twenty carbon atoms.

8. A lubricant composition comprising a major proportion of a viscous hydrocarbon oil and an oil-miscible stannous salt of an acidic reaction product obtained by reacting Pass with a, compound having the formula? in an amount suiiicient to exert detergent and anti-corrosive properties in the oil under heavy duty service, wherein Rn represents at least one oil-solubilizing alkyl group containing at least twenty carbon atoms.

,9. A lubricant composition comprising a major proportion of a viscous hydrocarbon oil and from about 0.01 per cent to about 5.0 per cent of an oilmiscible metal salt 01' a substitutedthio acid of I phosphorus having the general formula:

Esq-o Ego alkyl group containing at least twenty carbon atoms and M represents the hydrogen equivalent 01a metal.

. JOHN J. 

